The present invention relates generally to quantum systems and more particularly to an array of quantum systems within a volume bounded by conducting walls with applications to quantum information processing.
Quantum information processing is new paradigm of information processing wherein explicit quantum mechanical states and quantum mechanical phenomena and behavior are exploited for information processing applications. This feat is enabled by several peculiar properties found in quantum systems that are impossible to achieve in classical systems: the ability for a quantum system to be in a superposition of several of its eigenstates and the ability for several quantum systems to be entangled with one another. As such, quantum physics provides a basis for achieving computational power to address certain categories of mathematical problems that are intractable with current machine computation. Similarly to a classical bit where the state of a transistor in a processor, the magnetization of a surface in a hard disk and the presence of current in a cable can all be used to represent bits in the same computer, qubits represent different states. However, for a classical bit it is understood that its state must be 0 or 1. A qubit can be 0 or 1 or a superposition of both.
Several types of physical systems are possibly best suited for building a quantum computer. Such physical systems include, but are not limited to: silicon-based nuclear spins, trapped ions, cavity quantum-electrodynamics, nuclear spins, electron spins in quantum dots, superconducting loops and Josephson junctions, liquid state nuclear magnetic resonance (NMR), and electrons suspended above the surface of liquid Helium.
Historically, a liquid state NMR quantum computer (NMRQC) was the first physical system demonstrating many of the main concepts of quantum computing. In such a system the nuclear spins are placed in a strong magnetic field, creating “up” and “down” states of the nuclear spin (similar to a bar magnet) representing the logical |0> and |1> states. Subsequent quantum algorithms were identified allowing implementation of a three-qubit quantum search algorithm, a five-qubit order finding algorithm, the realization of an adiabatic quantum optimization algorithm, and a demonstration of Shor's factoring algorithm (factoring the number 15 using a 7-spin molecule). FIG. 1 illustrates a prior art NMR seven-spin molecule used to factor the number 15 into its prime factors 3 and 5. The NMRQC is very well-characterized and has several advantages including the seven spin states. However, NMRQC has several drawbacks including qubit systems limited to those nature naturally provides and also limited scalability. Currently, several types of physical systems are being pursued for quantum computing, including implementation of Josephson Junctions, superconducting loops, superconducting capacitors, and superconducting qubits. In addition to various approaches based on superconducting qubits, the most active areas of research involve trapped ions, and quantum dots. The largest quantum computer built in any of these systems to date consists of around 10 qubits, and most implementations are focused on the demonstration of a specific quantum algorithm or quantum state. However, there remain limitations on the number of collections of superconducting qubits possible in current physical systems.